This invention relates to a tensioner or tensioning device for fiber machines, such as a warping machine. More particularly, this invention relates to a magnetic non-contacting tension device for winding yarn.
Tensioning devices that are conventionally used in fiber machinery have a braking device that operates on the running of yarns such as thread, spun yarn, twisted yarn, and the like. Such devices include an advancement guiding member that is installed on the rotary shaft of the braking device and onto which yarn is helically wound. A tenser includes a pair of tenser-discs between which the yarn is sandwiched on the opposing working surfaces of the discs which have a bulged-out plate shape. A passage for yarn is formed so that the yarn passes from the inlet guide, tenser and advancement guiding member to the outlet guide. The tensioner is formed into a unit which is assembled onto a bracket.
In a conventional tensioner, a yarn advance guiding member or pulley is installed onto the shaft end of the rotary shaft of the braking device. The shaft protrudes from the insertion hole for a tubular member that stands on the bracket. The advance guiding member is supported rotatably on the tubular member via a bearing. Therefore, when yarn chips, and debris, enter from the opening of the insertion hole for the tubular member, the rotary shaft is braked by the friction force of sliding on such debris. As a result, a tension force larger than a set braking force is added to the yarn and breaking of the yarn occurs during its running. The objective of this invention is to solve such a problem and to offer a tensioner that can add a set tension to the yarn for a long period.
Additionally, in a conventional tension device, wound-up yarn can slacken and come off from the advance guiding member because of the inertial rotation of the advance guiding member when the yarn stops running. Also, when the yarn is rerun in this condition, it catches on the members that form the yarn path and it can be cut. On the other hand, a conventional tension device adds only a main tension, due to the brake force of the brake device to the yarn. The supplemental tension of the tenser is not needed. The general purpose properties of such conventional tension devices are poor. The objective of this invention is to offer a tension device that prevents the cutting of yarn because of slackening of the yarn caused by the inertial rotation of the advance guiding member, and to improve the general purpose properties of such tension device.